P20414: Indoor Dry Toilet Base

Detailed Design

Table of Contents

Team Vision for Detailed Design Phase


As a team we had planned to finish the small version of the prototype complete with the concrete being poured and casted. Ideally, we would’ve wanted to be able to confidently say that our process worked, and we can continue onto the life-sized toilet prototype.

Our team completed the inner and outer molds during this phase. There were difficulties with the assembly drawings which delayed our progress in getting into the construct lab to create the molds. The inner foam mold was completed in a day but then there was about a 1,2 delay before the drawings were complete and could be laser cut. There was also an issue with the wood and laser cutter which required cutting it over 2 hours instead of the original 30 minutes that the machine had scheduled.

Progress Report

The team plans to have the outer mold complete and assembled by the review. We would also like to pour the concrete but there is only a 1-day gap. This means if the outer mold has any issues, we will not be able to mix and pour the concrete.

The inner mold has been completed. The drawings have also been worked on and are almost finalized.

Outer mold has to be finalized and cut out and assembled. The owner is Patrick. The test plans must be completed. This owner is Jakob. The human subject testing application must be completed. Colin is the owner. Finally, the BOM has to be completed. Zyad is the owner.

The team will have further questions about the diverter and the materials available in Haiti. Although the inner mold is complete, it might be a better option to switch to plywood for the inner mold as well. More specific questions will be had after the testing is complete.

Prototyping, Engineering Analysis, Simulation

Plywood board after laser cutting

Plywood board after laser cutting

The team learned that certain types of plywood are way better than others when it comes to laser cutting. This was cheap wood since it was left over from another MSD team. It was not good for cutting and the board should have been a little bit thinner to make it easier to cut.

Combining prototype outer mold layers

Combining prototype outer mold layers

Prototype outer mold complete

Prototype outer mold complete

The outer mold for the prototype came together nicely. The team made sure to label the individual pieces before cutting them out and gluing them together so that we would know in what order they had to be combined.

Drawings, Schematics, Flow Charts, Simulations

Patrick designed the outer and inner mold for the toilet. Below are the detailed designs for the outer mold layers, inner mold layers, outer mold assembly and inner mold assembly.

Inner Mold Assembly.

Outer Mold Layer.

Outer Mold Assembly.

Zyad created manuals on how to assemble both the inner and outer mold. The instructions are crucial to ensure the successful repetition of the assembly process. The manuals explain in details how the molds should be assembled, how to use the tools like adhesive and releasing agent and how to account for the window and back opening. The assembly guides can be found here.

Outer Mold Assembly Guide.

Inner Mold Assembly Guide.

Window and Back Opening Concepts

Window and Back Opening Concepts

After following the instruction on how to assemble the molds and manufacturing the toilet, the wooden block and rod would be pushed out leaving opened space for the window and back opening in the toilet. Therefore, ER# 4, which corresponds to monitoring urine level, is fulfilled by this mold design and manufacturing process.

Bill of Material (BOM)

BOM for Prototype

BOM for Prototype

BOM for Life-Sized Toilet

BOM for Life-Sized Toilet

The BOM showed the team the actual cost of some of the materials that will have to be purchased when it becomes time to commence work on the life-sized toilet. This was also important since it gave the team a perspective as to how much these materials will cost when they are going to be purchased by the locals in Haiti. These costs are estimates as of the time of the detailed design review since the team does not have access to the real data. The total costs listed at the bottom of each are not cost per toilet being made, but rather the cost of all material and took required for one toilet to be made.

Detailed Design BOM.

Test Plans

Test plans were created that related back to each one of the engineering requirements that were established at the start of the project. Each Test plan has the tools required and the plan for how to actually perform the test. Seen below is an example of a test plan.

Test Plan Example

Test Plan Example

The teams test plans can be split into 2 categories. One involves human testing in which the team will need subjects to fill out forms and use the toilet to see how it performs. The other category is a physical category. These testing include testing the actual physical parts of the toilet. As an example weight would be a property that will be tested.

Full file with all test plans with associated ERS can be found here: Test Plans.

Risk Assessment

More risks were added for the next phase when MSD is resumed next semester. Not all risks were added however. Next steps rely on the small prototype failure or acceptance. Risks A seperate tab was also inserted showing the removed risks from previous phases. An example of added risks is shown below.

Added Risks Example

Added Risks Example

The full file can be found here: Risk Management File.

Design Review Materials

Plans for next phase

As a team we need to finish the prototyping of the small toilet. We have planned 2 days to attach the fiberglass and then another day to mix and pour the concrete.

As a team we need to really start focusing on the diverter for MSD2. We have a solid plan for building the life-sized toilet but have not been focused on the diverter as much. The team also has to focus more on risks. We have gotten better with the planning but still ended up 2 days behind this phase.

Z 3 week plan.

Patrick 3 week plan.

Colin 3 week plan.

Jakob 3 week plan.

The to do list for the rest of the semester can be seen down below

Plans for this semester

Plans for this semester

A general to do list can be found below. This has to be reviewed within the first two weeks upon returning next semester.

General to do list for MSD2

General to do list for MSD2

The Gantt chart can be found here. Additional time that is labeled as "Class" is reserved for the unknowns or risks that occur: Gantt File.

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